He said he felt anger and depression when the coalition government first came to power demanding health reforms that some people thought not possible.

But he thanked healthcare managers at the NHS Confederation Conference in Manchester yesterday for the achievements in the last year which he called remarkable.

Politicians were however warned that if they sought to make improvements and savings by trying to improve efficiency alone, the NHS would be in a ‘very dangerous place’.

Sir David praised the reconfiguration proposals in north west London published yesterday which include closing four out of nine A&E departments and manning the remaining emergency departments in the area with more consultants.

He said: ‘Without political leadership, it's quite difficult in the circumstances to have this debate with the public in this country about what services we can afford, free at the point of use and available to all, within financial constraints that we will have, not just over the next two or three years but probably for as long as all of us will be in the NHS.’

Enoch Powell's ‘water tower speech’ made in 1961 when he was health minister calling for the closure of NHS asylums was cited by Sir David as the sort of speech politicians should be making today.

He said: ‘In lots of ways, it's the sort of speech we need our national politicians to make at the moment. It's being honest with the public about the nature and scale of change that's required in order to live in a world where we have great outcomes for patients, universally available, but within the resources that we have.’

Sir David called for using terms that the public understands when talking about improving outcomes, for example talking about ‘lives saved’ and increasing life expectancy.

A public consultation on the proposals in north west London is to run from July to October, with the proposed changes being made early next year.